1. Field of the Invention
The present invention relates to a cooling device of an image forming apparatus, and in particular, to a structure of a steel case to be used for cooling a power source unit, a power source circuit board and the like by sending air by a fan motor.
2. Description of the Related Art
An image forming apparatus such as a Multi Functional Printer forms an image by forming an electrostatic latent image on a photo conductor, transforming an image developed by a developer such as toner on a recording medium, and fixing the image by heating with a fixing device or the like. In addition, in order to supply a low voltage power and a high voltage power to each device for forming an image, a power source unit, a low voltage power source circuit board, and a high voltage power source circuit board are incorporated in the image forming apparatus. The power source unit generates heat when it supplies a power and each power source circuit board generates heat because a power transistor, other heat generation parts and the like are mounted on it. As an internal cooling device to discharge heat to the outside of the apparatus, a fan motor is generally used.
In recent days, miniaturization is required for the image forming apparatus and further, in order to achieve silence, reduction of a noise from a fan motor is also required for the image forming apparatus. In order to reduce the noise from the fan motor, it is necessary to reduce the rotation number of the fan motor or the number of fan motors themselves, however, the cooling efficiency is lowered in any case.
In Japanese Patent Laid-Open application No. 2004-93708, an image forming apparatus is disclosed, wherein cooling efficiency is increased by arranging an engine circuit board, a high voltage power source circuit board, and a low voltage power source circuit board along an inlet path of air induced by the fan motor.
In addition, as shown in FIG. 6, in order to send air efficiently, it is considered to place a duct. FIG. 6 shows a condition that an image forming apparatus is seen from its side. With reference to FIG. 6, an operation part 2 that is operated by a user is provided at a front side of a main body 1, and a reading part 3 for reading an image of an original is located above the main body 1. In the main body 1, a power source unit 4 as a heating source is incorporated.
In addition, as shown in FIG. 6, in order to send air efficiently, it is
At a rear side of the main body 1, a control part 5 is provided. Here, the control part 5 is represented by a dashed line and the interior portion of the control part 5 is shown by an outlined sectional view. In the control part 5, a sheet metal 6 is provided, and on this sheet metal 6, a power source circuit board 8 is attached. On the sheet metal 6, a duct 7 is formed, and the front end of this duct 7 is elongated and positioned at the vicinity of the power source unit 4 of the main body 1. At the further rear surface of the further upper part from the power source circuit board 8, a fan motor 9 is mounted. The cooled air is blown on the power source circuit board 8 by the fan motor 9 and the cooled air is sent to the power source unit 4 via the duct 7. As a result, it is not necessary to mount the fan motor specifically for the power source unit 4 and silence can be achieved by executing cooling of the power source circuit board 8 and cooling of the power source unit 4 by one fan motor 9.
In the example shown in FIG. 6, the shape of the duct 7 becomes complicated, so that the manufacturing cost of the sheet metal 6 is made higher and a problem, for example, the limitation such as a size of the inside of the device or the like may occur when the duct 7 is arranged.